"because of a fluke" is correct and can be used in written English.
You can use it to refer to a strange or unexpected result, such as in the sentence "He won the lottery because of a fluke."
I'm grateful my student loan is gone, but not that it was because of a fluke.
But manufacturing losses in July eased to 52,000, largely because of a fluke in the auto industry.
The Vikings are an angry group after falling to Green Bay because of a fluke play on Monday night.
FRB 121102 is the only one they have witnessed more than once, and they are still not certain whether that is because of a fluke of timing or something more fundamental.
It has been widely reported that Hastings got his big story because of a fluke – the eruption of Eyjafjallajökull volcano in Iceland that trapped McChrystal and his team in Paris where they were on official business.
Lest you wonder how a man that clueless could be employed in academia anywhere below the North Pole, know that he can boast his job at an obscure agricultural college only because of a fluke.
Few did in 2003 in Maryland, when because of a scheduling fluke, some 16-year-olds were allowed to cast ballots in the Baltimore mayoral primary, said Matthew A. Crenson, a political science professor at Johns Hopkins University.
Because of a legislative fluke, studios realized, they could reap tax deductions up front if they set up film companies in Berlin, and German financiers also started their own production companies.
Thanksgivukkah 2013 is happening because of a rare fluke between the lunisolar Hebrew calendar and the Gregorian calendar in which they both sync up.
Because of a randomization fluke, 14 of the 22 people assigned to the no-lens condition were assigned to the throwing task.
"When I was younger I captained my school football team to a cup final but I think that was a bit of a fluke because I was not very good before or after that, or probably during.
